Multiwavelength Study on Solar and Interplanetary Origins of the Strongest Geomagnetic Storm of Solar Cycle 23

TL;DR

This study analyzes the solar and interplanetary origins of the strongest geomagnetic storm of Solar Cycle 23, using multiwavelength observations to trace CMEs and magnetic clouds leading to a super-storm on Earth.

Contribution

It provides a detailed multiwavelength analysis of the solar sources and interplanetary propagation of CMEs responsible for a major geomagnetic storm, highlighting the role of magnetic cloud interactions.

Findings

Two successive CMEs originated from the same filament channel.

The CMEs interacted and merged, leading to a super-storm with Dst peak of -472 nT.

Interplanetary magnetic clouds maintained their identity during propagation.

Abstract

We study the solar sources of an intense geomagnetic storm of solar cycle 23 that occurred on 20 November 2003, based on ground- and space-based multiwavelength observations. The coronal mass ejections (CMEs) responsible for the above geomagnetic storm originated from the super-active region NOAA 10501. We investigate the H-alpha observations of the flare events made with a 15 cm solar tower telescope at ARIES, Nainital, India. The propagation characteristics of the CMEs have been derived from the three-dimensional images of the solar wind (i.e., density and speed) obtained from the interplanetary scintillation data, supplemented with other ground- and space-based measurements. The TRACE, SXI and H-alpha observations revealed two successive ejections (of speeds ~350 and ~100 km/s), originating from the same filament channel, which were associated with two high speed CMEs (~1223 and ~1660 km/s, respectively). These two ejections generated propagating fast shock waves (i.e., fast drifting type II radio bursts) in the corona. The interaction of these CMEs along the Sun-Earth line has led to the severity of the storm. According to our investigation, the interplanetary medium consisted of two merging magnetic clouds (MCs) that preserved their identity during their propagation. These magnetic clouds made the interplanetary magnetic field (IMF) southward for a long time, which reconnected with the geomagnetic field, resulting the super-storm (Dst_peak=-472 nT) on the Earth.